58 ' GRAMINE^. 



Bractlet hairy; rachilla naked . . . . 26. Arundo. 



Braetlet naked; rachilla hairy 27. Phkagmites. 



B. Rachilla and bractlet naked, or if hairy the hair.s much shorter than the 



bracts and bractlet; stigmas (in ours) plumose, comparatively short, either 



sessile or raised on a short style, protruding from the sides of the bractlet. 



Spikelets of two kinds at each node, very dissimilar in form, one perfect and 



1 to 3-flowei ed; the others sterile and composed of many empty braf tlets. 



Perfect spikelets 1-flowered, the sterile consisting of about 10 empty bractlets 



which are obtuse .35. Lamaeckia. 



Spikelets alike in form .though sometimes dioecious. 

 Flowers dioecious; rootstoCK perennial. 

 Spikelets 8 to 16-fl.owered; rootstock very stout and creeping, scaly; panicle 



dense, ovoid; grasses of salt-marshes or alkali soils . . 32. Distichlis. 

 Spikelets 2 to 6-flowered; rootstock tufted or if creeping then long and 



slender 36. PoA. 



Mowers all perfect, or perfect and imperfect in the same spikelet. 

 Bracts and bractlets awnless. 

 Bractlet 1 to .3-nerved. 

 Annuals; panicle more or less lax; spikelets many (sometimes 70)- 

 flowered, the flowers densely imbricate; palea persistent after the 



bractlet and achene have fallen 2S. Eraqeostis. 



Perennials; panicle contracted and spikelike, dense or slightly iaier- 

 rupted, silvery shining; spikelets 2 to 7 (rarely only l)-flowered. 



29. KCELEEIA. 



Bractlet 3 to 5-nerved. 

 Perennials; uppermost flower-enclosing bractlet enwrapping 1 to 3 

 smaller empty bractlets, which in ours are truncate-clavate .... 



30. Melica. 

 Bractlet 5 to many-nerved. 



Spikelets large, flattened, ovate, somewhat cordate at base; bractlet very 



obtuse, concave, becoming ventricose; annuals , . 33. Briza. 

 Spikelets not cordate, mostly smaller. 

 Bractlet laterally compressed, mostly keeled, the margins or nerves 

 below clothed with cobwebby hairs, or pubescent, its lateral nerves 

 arched, converging above toward the mid-nerve. 36. PoA. 

 Bractlet rounded on the back, at least below, naked at the base, its 

 lateral nerves nearly parallel, scarcely or not at all converging. 



37. Panicui.akia. 



Either bracts or bractlets awned, awn-pointed or mucronate (in Koeleria). 



Palea with conspicuously toothed marginal wings on the keels; bractlet 



with a straight, rigid awn; annuals of wet meadows, with weak 



stems, and pale greenish-yellow foliage 31. Pleuropogon. 



Palea without marginal wings on the keel. 

 Panicle contracted and spikelike, dense or slightly interrupted, silvery- 

 shining 29. KCELEEIA. 



Panicle 1-sided, glomerate or interrupted; spikelets in dense, 1-sided 



fascicles 34. Dactylis. 



Panicle more or less lax; not dense and spibelike. 

 Stigmas plainly arising at or near the apex of the ovary; ovary and 

 achene in most cases smooth; bractlet not notched or 2-lobed, 



usually awned or awn-pointed 38. Festuca. 



Stigmas plainly arising below the apex of the ovary, oh the anterior 

 portion; ovary and achene crowned by a little appendage or tuft 

 of short hairs; achene always adnate to the palea; bractlet usually 

 distinctly notched or shortly 2-lobed at the apex, with an awn 

 between the notches . . . . 39. Bromus. 



26. ARUNDO L. 



Perennial reeds; stems tall, stout, erect. Leaf-blades broad, flat. 

 Spikelets 2 to 6-flowered, in a dense and somewhat spreading panicle. 

 Bracts somewhat unequal, keeled, 3-nerved. Rachilla naked, jointed 

 above the bracts and between the flowers. Flowers crowded, all 

 perfect or the upper staminate. Bractlet slender, 2-toothed and with 



